Search Publications
A study of solar energetic particle events of 1997-2006: Their composition and associations
Cane, H. V.; Richardson, I. G.; von Rosenvinge, T. T.
We examined the properties and associations of 280 solar proton events that extended above 25 MeV and occurred in the years 1997-2006. The properties include early peak intensities of five species over several energy ranges and the intensity-time profiles. Solar event associations were made for as many events as possible. The solar parameters dete…
Reconstruction of solar spectral irradiance since the Maunder minimum
Solanki, S. K.; Krivova, N. A.; Vieira, L. E. A.
Solar irradiance is the main external driver of the Earth's climate. Whereas the total solar irradiance is the main source of energy input into the climate system, solar UV irradiance exerts control over chemical and physical processes in the Earth's upper atmosphere. The time series of accurate irradiance measurements are, however, relatively sho…
Sun to 1 AU propagation and evolution of a slow streamer-blowout coronal mass ejection
Luhmann, J. G.; Li, Y.; Lynch, B. J. +4 more
We present a comprehensive analysis of the evolution of the classic, slow streamer-blowout CME of 1 June 2008 observed by the STEREO twin spacecraft to infer relevant properties of the pre-eruption source region which includes a substantial portion of the coronal helmet streamer belt. The CME was directed ∼40° East of the Sun-Earth line and the He…
Understanding large SEP events with the PATH code: Modeling of the 13 December 2006 SEP event
Verkhoglyadova, O. P.; Cohen, C. M. S.; Mewaldt, R. A. +7 more
The Particle Acceleration and Transport in the Heliosphere (PATH) numerical code was developed to understand solar energetic particle (SEP) events in the near-Earth environment. We discuss simulation results for the 13 December 2006 SEP event. The PATH code includes modeling a background solar wind through which a CME-driven oblique shock propagat…
Numerical simulation of the 12 May 1997 CME Event: The role of magnetic reconnection
Owens, M. J.; Crooker, N. U.; Gombosi, T. I. +4 more
We perform a numerical study of the evolution of a Coronal Mass Ejection (CME) and its interaction with the coronal magnetic field based on the 12 May 1997, CME event using a global MagnetoHydroDynamic (MHD) model for the solar corona. The ambient solar wind steady-state solution is driven by photospheric magnetic field data, while the solar erupt…
Observations of X-ray and EUV fluxes during X-class solar flares and response of upper ionosphere
Mahajan, K. K.; Lodhi, Neelesh K.; Upadhayaya, Arun K.
Most studies dealing with solar flare effects in the upper ionosphere, where ionization is caused by EUV photons, have been based upon X-ray fluxes measured by the SOLRAD and GOES series of satellites. To check the validity of such studies, we compare simultaneous observations of GOES X-ray fluxes and SOHO EUV fluxes for 10 X-class solar flares wh…
Characteristics of ground-level enhancement-associated solar flares, coronal mass ejections, and solar energetic particles
Cho, K. -S.; Firoz, K. A.; Hwang, J. +7 more
Ground-level enhancements (GLEs) are sudden, sharp, and short-lived increases in cosmic ray intensities registered by neutron monitors. These enhancements are known to take place during powerful solar eruptions. In the present investigation, the cosmic ray intensities registered by the Oulu neutron monitor have been studied for the period between …
An empirical model for prediction of geomagnetic storms using initially observed CME parameters at the Sun
Cho, K. -S.; Kim, K. -H.; Moon, Y. -J. +7 more
In this study, we discuss the general behaviors of geomagnetic storm strength associated with observed parameters of coronal mass ejection (CME) such as speed (V) and earthward direction (D) of CMEs as well as the longitude (L) and magnetic field orientation (M) of overlaying potential fields of the CME source region, and we develop an empirical m…
An empirical relationship between coronal mass ejection initial speed and solar wind dynamic pressure
Cho, K. -S.; Kim, K. -H.; Moon, Y. -J. +3 more
Interplanetary shocks that precede coronal mass ejections (CMEs) are mainly responsible for sudden impulses, which are characterized by a simple step-like increase in the horizontal H component. Such a magnetic field change has been explained as a compression of the magnetosphere by the passage of a sudden increase in the solar wind dynamic pressu…
A new approach for deriving the solar irradiance from nonflaring solar upper atmosphere plasmas at 2 × 104 ≤ T ≤ 2 × 107 K
Fontes, C. J.; Landi, E.; Doschek, G. A. +7 more
We propose a new approach for deriving the solar irradiance due to the emission by solar upper atmosphere plasmas at 2 × 104 ≤ T ≤ 2 × 107 K for wavelengths shorter than 800 Å. Our approach is based on a new understanding of the properties of the solar upper atmosphere; specifically, the discovery that the majority of emissio…